Metodologias analíticas para determinação de ricinina em amostras biológicas no diagnóstico das intoxicações por Ricinus communis

Ricinus communis, known as castor bean, is an oilseed with worldwide distribution and is important in poisoning domestic animals. Its complex toxicity involves different types of toxins, such as ricin and ricinin, which are present in various plant parts and in residues from castor oil production. The manifestation of poisoning varies according to the amount of material ingested, species involved, and individual susceptibility, including gastrointestinal signs due to the action of ricin and neurological symptoms due to the action of ricinin. The present study aims to develop and validate an analytical methodology for determining ricinin levels in urine, liver, and bovine ruminal fluid samples, for use as an auxiliary chemical marker in diagnosing poisoning by R. communis. A methodology was developed using high performance liquid chromatography (HPLC) with ultraviolet detection, and another was used using thin-layer chromatography (TLC) in ruminal content. The TLC methodology generates qualitative results but is simple to implement and has a low cost. In this study, the detection of ricinin by TLC showed better sensitivity using fluorescence in its evaluation (0.5 µg) than after development with the Dragendorff reagent (1.0 µg). However, given the samples' very low concentrations of ricinin, this methodology may not be sensitive enough for many cases. The HPLC methodology developed in this study showed the detection limit (LD) and quantification limit (LQ) of ricinin varying according to the wavelength used, being lower when using 208 nm, followed by 308 nm and 315 nm. In liver samples, the LD was 0.375 μg/mL (using a wavelength of 218 nm) and 1.25 μg/mL (315 nm) and the LQ was 1.25 μg/mL (218 nm) and 4.175 μg/mL (315 nm). For rumen fluid and urine samples, the LD was 0.15 μg/mL (218 nm) and 0.5 μg/mL (315 nm) and the LQ was 0.5 μg/mL (218 nm) and 1.67 μg/mL (315 nm). Thus, the detection of ricinin to confirm poisoning in animals due to consumption of castor beans can be done using the extraction methodology presented in this work and analysis by HPLC and UV-Vis detection of liver, urine, and ruminal fluid samples. On the other hand, TLC analysis is unsuitable for confirming cases of poisoning by castor beans in ruminal fluid.